Armour

For equipment classified as armour, see Armour (equipment).

For the basic passive skill, see Armour (passive skill).

Armour is a form of defence that reduces incoming physical damage from hits. Along with Evasion and Energy shield, Armour is one of the three defence types that can implicitly appear on equipment. Unlike resistance, Armour reduces damage by up to a constant value, rather than a proportion of the total damage: every 10 points of Armour blocks up to 1 physical damage per hit. The absolute amount of damage reduced gets closer to the maximum the more damage the hit does.

Armour rating can be increased by wearing equipment, taking certain passive skills, using spells such as Molten Shell, and drinking a Granite FlaskGranite FlaskLasts 4.00 Seconds
Consumes 30 of 60 Charges on use
+1500 to ArmourRequires Level 27Right click to drink. Can only hold charges while in belt. Refills as you kill monsters..

Supposedly the most armour monsters have in the game is about 983.

Mechanics

Damage reduction from armour only reduces physical damage taken from hits. Elemental damage and damage-over-time are not affected.

rule of thumb

• To prevent one third of damage, you need armor 5 times the damage (e.g. 500 Armor for 100 damage)
• To prevent half of damage, you need armor 10 times the damage (e.g. 1000 Armor for 100 damage)
• To prevent two thirds of damage, you need armor 20 times the damage (e.g. 2000 Armor for 100 damage)
• To prevent three quarters of damage, you need armor 30 times the damage (e.g. 3000 Armor for 100 damage)
• To prevent 90% of damage, you need armor 90 times the damage (e.g. 9000 Armor for 100 damage)

Formulas

For a step by step calculation of formulas, see Armour/math.

The amount of damage reduction is a function of armour rating and the damage taken. Damage reduction is capped at 90%.

Relative Damage Reduction (Base Formula)

This is the base formula all other formulas are based upon. It is used to calculate the damage reduction factor, i.e. the percentage by which the damage is reduced.

$DR(A, D_{raw}) = {A \over A + 10 * D_{raw}}$

Required Armor

To calculate the armor you need to mitigate a given amount of damage at specific ratio, you can use this formula:

$A(D_{raw}, DR) = {DR * 10 * D_{raw} \over 1 - DR}$

Reverse Damage

You can also calculate the raw damage that would have resulted for a given damage reduction and armour value:

$D_{raw}(A, DR) = {A \over 10 * DR} - {A \over 10}$

Resulting Damage

To calculate the net damage (i.e. the damage after damage reduction, the following formula can be used:

$D_{net}(A, D_{raw}) = {10 * {D_{raw}}^2 \over A + 10 * D_{raw}}$

Absolute Damage Reduction

Another way of looking at it is in terms of absolute damage reduction:

$DR_{abs}(A, D_{raw}) = {A * D_{raw} \over A + 10 * D_{raw}}$

Defense factor

$DF(A, D_{raw}) = {A \over 10 * D_{raw}} + 1$

examples

For example, if you have 1200 armour rating this chart indicates how much damage will be reduced by:

The vertical axis is damage reduction percent. The bottom axis is original damage.

Therefore we can conclude:

• If raw damage is much less than Armour / 10, raw damage has a near-quadratic effect on net damage. Equivalently, in this regime raw damage has a near-linear effect on net DPS if the raw DPS is held constant.
• If raw damage is much greater than Armour / 10, raw damage has a near-linear effect on net damage. Equivalently, in this regime raw damage has little effect on net DPS if the raw DPS is held constant.
• Against attacks of a fixed raw damage, armour has a linear effect on the number of attacks it takes to deplete a certain amount of hit points.

Skills

The Determination aura increases armour of the character and nearby allies. The Molten Shell and Vaal Molten Shell skills temporarily grants player additional armour.

Passive skills

There are passive skills that grant armour bonuses.

Armour rating

These passive skills grant increased armour rating or additional base armour rating. The Iron Reflexes keystone is special in that it converts evasion rating to armour rating.

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Armour rating on shields

These passive skills grant increased armour rating from equipped shields.

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Miscellany

These passive skills are related to armour, but do not fit into any other category.

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